One of our most frequently asked questions on the Forums and via email is how to produce a calibration for the Cheapstat potentiostat. The Cheapstat potentiostat returns measured current values as raw unitless integers read from the ADC (analog to digital converter) at the output of the transimpedance amplifier (current to voltage converter). These integer values are proportional to the current flowing into the working electrode. To convert these unitless integer values to current measurements you need to use a calibration. This can be done using a dummy cell consisting of a single resistor of known value R.
We recently designed a potentiostat dummy cell which can be easily used to perform this calibration. In its simplest configuration it has a single resistor in position R1 where counter and reference electrodes are connected to one end of the resistor (e.g. a 50K resistor) and the working electrode is connected to the other end. In this configuration the potentiostat can be used to set-up a voltage across the resistor while measuring the current passing through it. In other configurations the dummy cell can be used for different tests and demonstrations.
We have posted a short document online here describing how to use the dummy cells to calibrate the Cheapstat. The dummy cells are now in the store and are available as either a blank PCB or pre-assembled with a 1, 10, 50, 100K or 1M Ohm resistor.